I have two sealed boxes of this paper, 11 inches by 100 feet. Says "Open in Dark Room Only" and "Ilford Panchromatic Bromide, Waterproof Base" No date, but it is stamped with dots; the code: 252BE. Feb. 1952, perhaps? I am wondering what exactly this is and what it is good for. I have a suspicion that it was intended for carbro prints, as I got it from the supply of a photographer who did do carbro prints, among other things...and carbro prints do necessitate the use of roll paper to help with registration. In this case, the surface of the paper would be different than standard printing paper. Any thoughts on what it is and what it's good for? If it is in any way desirable unopened, I don't want to bust it out of the box until I've decided for sure not to sell it.